Conventionally, in order to collect waste plastics resulting from containers, electric appliance wastes, information equipment wastes, or the like as regenerative resins, a known cyclone type airflow applied separation device uses, as a mixture to be processed, crushed plastic granular material containing many lightweight foreign substances such as paper slips that is crushed to have a grain diameter of 10 mm or less and subjected to dry washing mainly for separating a degraded front surface layer (see, for example, Patent Literature 1).
Note that the cyclone type refers to a separation system that turns dust-containing gas (same as gas containing a mixture to be processed) and separates by centrifugalization powder and granular material or the like from the gas to be collected or classified.
Here, attention is given to the point that a centrifugal falling airflow containing granular material is collected as a rapidly-accelerated vortex flow at the lower space of the tip opening of an airflow discharge tube inside a cylinder by a partition plate with an opening at the center thereof, which promotes the function of separating the lightweight foreign substances from a solid content and increases floating separation efficiency with an upstream flow.
However, since the crushed waste plastics are required (allowed) to have a grain diameter of 10 mm or less, it is presumed that the distribution of the grain sizes is complex and bulk specific gravity is different. In short, it seems that the granular solid content resulting from the crushing and the lightweight foreign substances or the like with small bulk specific gravity such as a separated front surface abrasive layer (crushed fine powder), paper slips, and tape slips are floated and selected with the application of a cyclone type airflow.
On the other hand, there have been known some proposals that separate and collect used blast material (equivalent to the abrasive of the present invention) (see, for example, Patent Literatures 2, 3, 4, and 5). These conventional examples generally relate to filter separation, screening selection, wind selection, or floating selection.